Front parts for modules are used for the sealing and closing of modules chassis for electronic devices to achieve the electromagnetic decoupling of the module chassis from its environment. During that, the electronic module within the module chassis has to be protected against external electromagnetic interferences and on the other hand, the emissions of the modules have to be minimized so that only a minor disturbance of the environment is generated by the electronic. Therefore, a high shielding effect of the module chassis against high frequency electromagnetic alternating fields is necessary.
The weak points of the electromagnetic shielding are the vertical slots, occurring between two adjacent front parts, respectively between front part and chassis.
The width of the slots heavily depends on the tolerances of the front panels that are inserted into the module chassis. Flexible contact materials, which should cause a HF-tight electrical bonding of the opposite edges of two adjacent front panels, are therefore inserted between the front panels.
Front panels for plug-in modules that have a groove on the side in its narrow edges in which spring elements are mounted are known from the patent letter DE 195 44 835 C1. The spring elements point in the plug-in direction and exceed the thickness of the front panel. Such contact springs can easily be damaged by the user during the removal or insertion. Furthermore, they have the disadvantage that the contact springs have no lateral guide and can therefore only sustain limited lateral pressure.
A contact arrangement is known from DE 196 11 719 A1 for the manufacturing of an HF-tightness between two front panels, adjoining at their front sides. There, different sealing elements and contact springs are proposed. Because of the standard default for the thickness of the front panels only very small tightness elements can be inserted, which can only insufficiently fill the slots between adjacent modules. The proposed contact springs bypass this problem. Since they exceed the thickness of the front panel in the direction of insertion, the contact springs can easily be damaged by the user when handled during insertion and removal.
One-piece, in cross-section U shaped front panels, are known from the disclosure statement DE 36 04 860 A1, which two side parts point in the plug-in direction and one side part is designed as contact strip and the other as glide spring strip for the acceptance of spring elements.
One-piece, in cross-section U-shaped front panels are usually manufactured from aluminum by extrusion. During this process, the material is subject to severe change in temperature, which results in shrinking and unexpected change in dimension. Subsequent pulling (straightening) also affects the production dimension. Therefore, the desired width of the front panels can only be achieved with large tolerances. The larger the front panel is, the larger the measuring tolerances will get. For very wide front panels the normative predefined tolerances cannot be maintained at all. For the production of one-piece front panels that are different in width a separate tool must be used for each width. This procedure requires a big and especially cost-intensive effort.
As a further disadvantage, the surface structure and the configuration structure of the material is altered during the extrusion. The effects especially appear with wide and at the same time thin-walled front panels. The front panels cannot be eloxadized in a uniform way. That leads to consuming and expensive post-production. No sophisticated, eloxadized front panels can be manufactured without post-production.